To use things that have been there for a long time.
In regards to the tourism industry, it's nice to have new facilities, however it's even better to restore buildings that have been there for a long time.
ご質問ありがとうございます。
この場合は、「昔からあるものを活かす」は英語で「To use things that have been there for a long time.」と言えます。
Emmaさんの例文も英訳しましょう。「観光業について話していて、新しい施設を作るのも良いが、昔からあるような建造物を再興させるのも良い」は英語で「In regards to the tourism industry, it's nice to have new facilities, however it's even better to restore buildings that have been there for a long time.」という風に言えます。
ご参考になれば幸いです。